A standard for Wireless Local Area Network technology is being developed as an IEEE (Institute of Electrical and Electronics Engineers) 802.11 standard. IEEE 802.11a and b use an unlicensed band at 2.4. GHz or 5 GHz, and IEEE 802.11b provides a transmission rate (or transmission speed) of 11 Mbps, and IEEE 802.11a provides a transmission rate of 54 Mbps. IEEE 802.11g provides a transmission rate of 54 Mbps, by applying OFDM (Orthogonal frequency-division multiplexing) at 2.4 GHz. IEEE 802.11n provides a transmission rate of 300 Mbps with respect to 4 spatial streams, by applying MIMO-OFDM (multiple input multiple output-OFDM). And, IEEE 802.11n supports a channel bandwidth of up to 40 MHz, and, in this case, IEEE 802.11n provides a transmission rate of 600 Mbps.